Transcript Probing of Nanostructured Surfaces at Attosecond Timescales

Probing of Nanostructured Surfaces
at Attosecond Timescales
Emma Catton
• 1st year PhD student in the Atomic Manipulation Group at NPRL
• Based in Birmingham for my first year then at Imperial College London to
concentrate work on the STM.
NPRL
Nanoscale Physics Research Laboratory
Current Group Interests
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Gold Fingers
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Finger like structures were produced by
scanning the STM tip at a step edge with
constant voltage bias and increasing
tunnel current.
Fingers were produced at 90˚ and 150˚ to
the discommensuration lines of the
heringbone reconstruction1.
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Other Work
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Dissociation of aromatic molecules on
silicon surfaces.
Manipulation of gold clusters on graphite.
Metal oxide semiconductors.
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(150nm x 150nm)
Finger Width 3nm - 8nm
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Q. Guo, F. Yin, R. Palmer, small (1) 76-79 (2005)
NPRL
Nanoscale Physics Research Laboratory
Proposed Work –TiO2 (110) Surface
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Why TiO2?
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Considerably well studied in the past the surface is now well characterised. This
makes it a good choice for studying new phenomena.
Many applications including photocatalyst, solar cells, white pigment, corrosionprotective coating and optical coating.
Irradiation by electrons or photons can give rise to desorption of O+ ions from the
surface via the Knotek-Feibelman process. Known as electron or photon stimulated
desorption (ESD or PSD).
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Proposed work
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Produce 1x1 reconstructed flat surface and investigate ESD at Birmingham
STM studies of surface before and after laser irradiation. Possible PSD?
Deposit metal such as Au onto surface. Gold is expected to diffuse to oxygen
deficient sites.
Nanostructures can be created.
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NPRL
Nanoscale Physics Research Laboratory
Nanostructured Surfaces
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Consider a thin film……
Acts as 1D quantum well
Quantum states can be studied using STS
(Scanning Tunneling Spectroscopy) or
photoemission spectroscopy.
Pump and probe technique can be used to
determine the lifetime of excited states. Electrons
can be looked at in real time by varying time delay
between pulses.
1-2 nm
~ 50nm
~ 50nm
Aim of my PhD
To combine fast photon pulses and STM allowing
analysis of surface processes at high spatial and
temporal resolutions. This will provide a better
understanding of the dynamical processes of atoms
and electrons on solid surfaces.
E.t  
NPRL
Nanoscale Physics Research Laboratory